1. Field of the Invention
The present invention relates generally to magnetic heads that are utilized with thin film hard disk data storage devices, and more particularly to the design and fabrication of a write pole for a perpendicular magnetic head.
2. Description of the Prior Art
Hard disk drives generally include one or more rotatable data storage disks having a magnetic data storage layer formed thereon. Data in the form of small magnetized areas, termed magnetic data bits, are written onto the magnetic layers of the disks by a magnetic head that includes magnetic poles through which magnetic flux is caused to flow. Magnetic flux flowing from a pole tip portion of the magnetic poles in close proximity to the magnetic layer on the disk, causes the formation of the magnetic bits within the magnetic layer.
In recent years, perpendicular magnetic heads have received renewed interest in the effort to extend data areal storage density. The increased demand for higher areal storage density has correspondingly fueled the exploration of a robust process to form the write pole of the perpendicular magnetic head. Current exploratory fabrication methods use an ion milling process to fabricate the write pole, in which a photolithographical pattern is image-transferred by reactive ion etching (RIE) into a material with a low ion milling rate using a bi-layer or tri-layer hard mask scheme. The hard mask then functions as a transfer mask to pattern the write pole into a full-film magnetic material. Since patterning is by a physical process, one major complication in developing a robust write pole fabrication process is the difficulty in removing mask overburden materials and flattening the surface of the wafer without damaging the write pole. As the dimensions of the write pole shrink and the requirements on the retention of the write pole thickness, width and shape become more stringent, a major challenge is to develop a manufacturable process that overcomes the inherent within wafer non-uniformity that often accompanies the conventional CMP process.